Pseudopterogorgia elisabethae, a purple frilly seafan, is a gorgonian commonly found in the shallow-water reefs of the tropical Atlantic including regions of the Caribbean. P. elisabethae is of particular commercial importance as it has been found to contain numerous biologically active small molecule compounds. Among these, pseudopterosins (also known as terpenes, e.g., diterpenes) have been shown to exhibit anti-inflammatory and analgesic properties, and are currently being used as topical agents in skin care products. In the biosynthetic pathway shown in FIG. 1, pseudopterosin/seco-pseudopterosins are generated from geranyl geranyl diphosphate (GGPP). A key step in this pathway is the cyclization of GGPP to elisabethatriene (compound 18). From elisabethatriene, the intermediate compounds 19-27 and pseudopterosin A are made. The identification of enzymes responsible for catalyzing key steps in this pathway, however, has been elusive. Identification of such an enzyme would facilitate the development of a chemoenzymatic method for the production of marine diterpenes.